in astronomy, zodiacal constellation lying between Aries and Gemini, at about 4 hours 20 minutes right ascension (the coordinate on the celestial sphere analogous to longitude on the Earth) and 16° north declination (angular distance north of the celestial equator). The constellation's brightest star, Aldebaran (Alpha Tauri), is of the first magnitude. The constellation also contains the Crab Nebula (M1) and the Pleiades and Hyades star clusters.